Ambient air includes a certain amount of water vapor amongst other gases. The amount of water vapor that ambient air can hold is dependent, in part, upon the temperature of the ambient air. Dew point is a measure of the temperature at which water vapor in ambient air will begin to fall out and condense upon a surface. In situations of high humidity such as a bathroom where a shower or other hot water sources are present, it is common for the dew point to be higher than the surface temperature of structures in the bathroom, such as the mirror. When the temperature of a mirror or other surface is below that of the dew point, water vapor from the ambient air will condense onto the surface of the mirror causing fogging.
One way to prevent condensation and fogging on a mirror is to maintain the surface of the mirror at a temperature higher than that of the dew point. This is most conveniently done by providing a source of heat to the mirror.
Heated mirrors have long existed in the art. Heated mirrors have fallen into two basic classifications. The first classification includes those mirrors that are heated by hot water drawn from the bathroom plumbing system. Heating a mirror by using hot water from the bathroom plumbing system has the obvious disadvantage in that the plumbing required might be complex and is subject to the risk of leaking.
The alternative approach is to heat the mirror by the use of electrical heating elements. Examples of such mirror, which utilize electrical heating elements, are described in the following prior art references: Catterson, U.S. Pat. No. 3,160,736; Feldman et al., U.S. Pat. No. 5,280,981; Ghiassy, U.S. Pat. No. 5,302,809; and Mischel, U.S. Pat. No. 5,408,069. All of the previously cited references disclose electric heating elements that are connected to an electrical source, which are secured to the backs of mirrors or wall behind the mirror for defogging them. However, all of these references fail to adequately protect the heating element and electrical connections from exposure to moisture or require additional materials used in combination with the element to uniformly heat the mirror surface.
Other prior art references disclose or suggest fogless mirrors, but do not provide a moisture resistant assembly for the protection of the heating element and electrical connections or for a lighted mirror. For example, Reiser et al., U.S. Pat. No. 5,406,049, discloses a fog-resistant mirror assembly including a conductive coating within the mirror thereby providing a heating element. Additionally, Rust, U.S. Pat. No. 3,530,275, and Reuben, U.S. Pat. No. 4,940,317, respectively, disclose resistant heating elements secured to mirrors per se. Furthermore, Winter, U.S. Pat. No. 5,904,874, discloses a resistance heating device that is incorporated as a plurality of layers in a bathroom mirror. Finally, U.S. Pat. No. 5,911,896 reveals a thin film heater element that can be laminated between two glass ceramic panels.
It is noted that the prior art references cited above are not specifically designed to be used in an environment where direct exposure to flowing water may occur. The devices disclosed in the previously mentioned references fail to provide a heating element adequately sealed from outside moisture. Furthermore, the previously cited references do not disclose a heating element enclosed in a moisture insulation assembly that will not absorb moisture or deteriorate when in contact with moisture, but still possesses the capability of uniformly and controllably transferring heat to a mirror surface. In addition, the prior art references do not provided for a lighted mirror.
Sellgren et al., U.S. Pat. No. 6,420,682, however, is designed to be used in an environment where direct exposure to flowing water may occur. Sellgren et al. discloses a fogless heated mirror that can be incorporated into a shower or bathtub surround and is incorporated herein by reference.
Lighted mirrors are known in the art, and are often used to provide improved visibility of the face especially for use when shaving or applying make-up or other facial skin preparations. Examples of lighted grooming mirrors are described in the following prior art references: Burton, U.S. Pat. No. 6,347,876; Chu, U.S. Pat. No. 5,997,149; and Goldstein et al., U.S. Pat. No. 6,441,969. All of the previously cited references disclose lighted grooming mirrors, however these mirrors are not adapted to be used in a wet environment such as a shower or bathtub surround. Zadro, U.S. Pat. No. 4,733,468, is designed to be used in a shower, however, the mirror is heated through the use of hot water and water is used to turn a small generator to power the light.
In recent years, architectural trends have moved toward the development of larger, more comfortable, more luxurious bathrooms in residential construction. These architectural trends have been in response to changes in lifestyle in which bathrooms have often changed from purely utilitarian areas to areas of greater convenience and luxury. For example, bathrooms in new construction and remodeling now often incorporate hot tubs or whirlpool tubs as well as luxury shower facilities.
Along with these changes has been a general trend toward increasing convenience items in bathroom facilities. Thus, it is now more desirable than in the past to be able to have a lighted fog-free mirror incorporated into a luxury shower or tub surround to accommodate such activities as shaving, hair coloring and other cosmetological activities. With this desire comes an increased concern for absolute electrical safety since the fog-free mirror may be exposed directly to water, more than a typical vanity mirror.
In addition, with the aging of the population, a mirror incorporated into the bathtub or shower surround presents enhanced convenience and also provides accommodations to certain types of disabilities. For example, persons with arthritis may find it much more comfortable to do fine motor tasks such as shaving in a warm moist environment. Therefore, the placement of a fog-free mirror in a shower or bathtub surround accommodates individuals with such conditions.